Optical redox ratio using endogenous fluorescence to assess the metabolic changes associated with treatment response of bioconjugated gold nanoparticles in streptozotocin-induced diabetic rats

Abstract

Fluorescence spectroscopic techniques have the potential to assess the metabolic changes during disease development and evaluation of treatment response in a non-invasive and label-free manner. The present study aims to evaluate the effect of mulberry-mediated gold nanoparticles (MAuNPs) in comparison with mulberry leaf extract alone (MLE) for monitoring endogenous fluorophores and to quantify the metabolic changes associated with mitochondrial redox states during streptozotocin-induced diabetic liver tissues using fluorescence spectroscopy. Two mitochondrial metabolic coenzymes, reduced nicotinamide dinucleotide (NADH) and oxidized flavin adenine dinucleotide (FAD) are autofluorescent and are important optical biomarkers to estimate the redox state of a cell. Significant differences in the autofluorescence spectral signatures between the control and the experimental diabetic animals have been noticed under the excitation wavelength at 320 nm with emission ranging from 350-550 nm. A direct correlation between the progression of diabetes and the levels of collagen and optical redox ratio was observed. The results revealed that a significant increase in the emission of collagen in diabetic liver tissues as compared with the control liver tissues. Moreover, there was a significant decrease in the optical redox ratio (FAD/(FAD + NADH)) observed in diabetic control liver tissues, which indicates an increased oxidative stress compared to the liver tissues of control rats. Further, the extent of increased oxidative stress was confirmed by the reduced levels of reduced glutathione (GSH) in diabetic liver tissues. On a comparative basis, treatment with MAuNPs was found to be more effective than MLE for reducing the progression of diabetes and improving the optical redox ratio to a near normal range in streptozotocin-induced diabetic liver tissues. Furthermore, principal component Laser Physics Letters

Evaluating Cell Metabolism Through Autofluorescence Imaging of NAD(P)H and FAD

“…Images courtesy of Jake D. Jones and Kyle P. Quinn. To see this illustration in color, the reader is referred to the web version of this article at www.liebertpub.com/ars effective in reversing diabetes progression as an antioxidant (1). A novel ''oxidative stress axis'' has also been proposed based on FLIM phasor analysis of oxidative stress that identified a unique long lifetime component thought to be a product of lipid oxidation (22).…”

Maturation‐ and degeneration‐dependent articular cartilage metabolism via optical redox ratio imaging

“…Normalization of the intensity to the laser power is used when optical redox ratio imaging is conducted using multiphoton microscopes, so we chose to use exposure time as the relative measure of power in this autofluorescent study. ImageJ software was used to calculate the optical redox ratio (ORR), defined as [FAD]/[NAD(P)H + FAD] 12,24,25 . Because the ORR is defined by the two individual intensities, in the case where one channel changes but the other do not, ORR can be driven by a single channel.…”

“…ImageJ software was used to calculate the optical redox ratio (ORR), defined as [FAD]/[NAD(P) H + FAD]. 12,24,25 Because the ORR is defined by the two individual intensities, in the case where one channel changes but the other do not, ORR can be driven by a single channel. Intensity over the full image was acquired, based on a preliminary analysis comparing the full image results to results from just cells (see Figure S3).…”

Imaging approaches for monitoring three‐dimensional cell and tissue culture systems

“…The ratio can help in understanding the governing metabolic state of cells [39], such as oxidative phosphorylation or glycolysis. This method has proven useful in quantitative studies of tissues that have undergone chemotherapy [39], to quantify the potential for metastatic development in breast cancer [40], and to study cell responses to treatment with bio‐conjugated gold nanoparticles in diabetic rats [41]. While another study has combined label‐free 3PEF with FLIM and Förster resonance energy transfer (FRET) for screening the change in metabolic activity of intracellular tryptophan and NAD(P)H that typically occurs in a variety of human diseases and other clinical conditions [42].…”